package com.wc.AlgoOJ._贪心.AG0405;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;

/**
 * @Author congge
 * @Date 2024/1/19 15:42
 * @description 小熊杂技
 * http://43.138.190.70:8888/p/AG0405
 */
public class Main {
    static FastReader sc = new FastReader();
    static PrintWriter out = new PrintWriter(System.out);
    static int n;
    static int N = 50010;
    static int[][] a = new int[N][2];

    public static void main(String[] args) {
        n = sc.nextInt();
        for (int i = 1; i <= n; i++) {
            for (int j = 0; j < 2; j++) {
                a[i][j] = sc.nextInt();
            }
        }
        Arrays.sort(a, 1, n + 1,(o1, o2) -> o1[0] + o1[1] - o2[0] - o2[1]);
        long totalW = 0;
        long maxS = Long.MIN_VALUE;
        for (int i = 1; i <= n; i++) {
            maxS = Math.max(maxS,totalW - a[i][1]);
            totalW += a[i][0];
        }
        out.println(maxS);
        out.flush();
    }
}

class FastReader {
    StringTokenizer st;
    BufferedReader br;

    FastReader() {
        br = new BufferedReader(new InputStreamReader(System.in));
    }

    String next() {
        while (st == null || !st.hasMoreElements()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return st.nextToken();
    }

    int nextInt() {
        return Integer.parseInt(next());
    }

    String nextLine() {
        String s = "";
        try {
            s = br.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return s;
    }

    long nextLong() {
        return Long.parseLong(next());
    }

    double nextDouble() {
        return Double.parseDouble(next());
    }

    // 是否由下一个
    boolean hasNext() {
        while (st == null || !st.hasMoreTokens()) {
            try {
                String line = br.readLine();
                if (line == null)
                    return false;
                st = new StringTokenizer(line);
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return true;
    }
}
